U-nut fasteners are used in the automotive and other industries for mounting various components, such as, for example, modules, door panels, bumper components such as fascia, and the like, upon underlying support panels or structures, plates, beams, and the like. U-nut fasteners are known to comprise a U-shaped spring clip of connected first and second arms, with a flexibly resilient annular hoop or retainer ring, having a central aperture, partially sheared from a first one of the arms; and an internally threaded sleeve or nut member integrally formed upon the other one of the arms of the U-shaped spring clip. The U-nut is mounted on one component, such as a support panel or plate, and is held thereon by the resilient annular hoop member biased against one side of the component, the other side of which rests against the inner surface of the second arm of the U-nut. The threaded sleeve or nut member threadedly receives a threaded bolt or similar type fastener which is passed through an aperture defined within a second component, whereby the U-nut and bolt fasteners can be fixedly secured together so as to in turn secure the two components one to the other.
U-nuts can be mounted upon a support panel or plate by inserting an edge portion of the support panel or plate into the space defined between the two arms of the U-nut fastener, and subsequently sliding the U-nut fastener onto the support panel or plate until the flexibly resilient annular hoop or retainer ring engages and becomes seated within a hole defined within the support panel or plate. The second one of the arms of the U-nut can be provided with an upwardly bent forward edge or lip portion to facilitate insertion of an edge portion of the support panel or plate between the two arms of the U-nut. The central aperture formed within the first arm of the U-nut, defining the annular hoop or retainer ring inner periphery, also permits passage therethrough of the bolt fastener, and serves to somewhat guide the bolt fastener into engagement with the internally threaded sleeve or nut member formed upon the second arm of the U-nut
It is has been known to distribute and use U-nuts as individual components randomly gathered in a container. Assemblers are required to handle each U-nut individually while manually installing the U-nuts in an assembly. The structure of U-nut fasteners can result in the interlocking or entanglement of such fasteners when randomly accumulated in a box or other storage or shipping container. Interlocking or entanglement of the fasteners prevents efficient packaging of the fasteners, and inhibits efficient and rapid use of such fasteners during installation procedures when the interlocked or entangled fasteners must first be unlocked or disentangled from each other.
U.S. Pat. No. 6,450,747 describes a U-nut fastener which permits and facilitates stacking or nesting of such fasteners into a collated strip. The internal diameter or diametrical extent of the central aperture defined within the annular hoop or retainer ring is substantially the same as the external diametrical extent of the internally threaded sleeve or nut member such that the annular hoop or retainer ring of a first U-nut fastener can be fitted upon or over the upstanding threaded sleeve or nut member of a second U-nut fastener, whereby the fasteners can be nested or stacked in an array or collated strip. U.S. Pat. No. 6,711,809 describes a tool that can be used for installing individual U-nuts from a collated strip of the U-nuts.
Collated U-nuts as described have achieved benefits and advantages, but also have some limitations. For example, the design is less suitable for U-nuts of thinner materials than for U-nuts of thicker materials. Further, when the use requires deformation of the threaded sleeve or nut to establish prevailing torque characteristics, it can be difficult to maintain the required dimensional tolerances to achieve engagement of one U-nut to another in the stacked arrangement.